Contactless integrated circuit card with real-time protocol switching function and card system including the same

ABSTRACT

A contactless integrated circuit (IC) card can include: an analog interface block operable to demodulate a received radio frequency (RF) signal into multiple versions thereof according to a first plurality of communication protocols, respectively; a controller operable to select from among a second plurality of communication protocols; and a universal asynchronous receiver/transmitter (UART) operable to select one of the demodulated versions of the RF signal according to the selected protocol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. non-provisional patent application Ser.No. 10/939,518, filed Sep. 14, 2004, which claims priority under 35U.S.C. §119 of Korean Patent Application 2003-63625 filed on Sep. 15,2003, the entire contents of each of which are hereby incorporated byreference.

BACKGROUND OF THE PRESENT INVENTION

Data transmission systems are well known and widely used to exchangeinformation and conduct transactions with remotely positioned portabledata devices. Such portable data devices are commonly referred to ascards, smart cards, or tags. Likewise, data transmission terminals arecommonly referred to as card readers. In such a data transmissionsystem, a transaction begins when a card enters the excitation field ofthe terminal/reader. In particular, the terminal produces a power signalas well as a data signal (also referred to as an information signal) andtransmits the information signal using a carrier signal. It is thedetection and reception of the carrier signal that remotely powers thecard, and enables the card circuitry to perform its intended function.

Remotely powered (i.e., contactless) data devices (i.e., cards) can beused to perform a variety of tasks, including theft prevention,personnel or material identification and control, automatic farecollection, money and service transaction recording and control, and thelike. While ID tags may be less complex, so-called smart cards tend tobe more complex and may include one or more processors, as well as localmemory to store and process information. A particular variety of thecontactless IC cards (or contactless smart cards) is known as a vicinitycard and uses a communication protocol called the ISO/IEC 14443standard. Physical characteristics of a vicinity IC card, its radiofrequency (RF) power and signal interface, and its initialization andanti-collision and transmission protocol are defined in ISO/IEC 14443.Specifically, two communication signal interfaces, referred to as type-Aand type-B, are described in ISO/IEC 14443.

In the type-A interface, interfacing between a card reader (or aterminal) and an IC card is performed using the technique of amplitudephase-shift keying (ASK) 100% modulation of the RF operating field, anddata to be transmitted are coded in the format of a modified millercode. In the type-B interface, interfacing between a card reader (or aterminal) and an IC card is performed using ASK 10% modulation and datato be transmitted are coded in a format of NRZ-L non-return-to-zerolevel (NRZ-L) code. Since the type-A and type-B interfaces are describedin detail in ISO/IEC 14443, a detailed description about them will beomitted.

IC cards according to the Background Art support either the type-A ortype-B interface. As described above, since the type-A and type-B codingand modulation are different from each other, an IC card supporting oneof the communication signal interfaces can be used only in a card readersupporting the corresponding communication signal interface. If a cardreader supports the type-A communication protocol, it is impossible touse with it an IC card supporting only the type-B interface, andvice-versa.

SUMMARY OF THE PRESENT INVENTION

At least one embodiment of the present invention provides a contactlessIC card capable of improving the compatibility by switching (e.g.,adaptively) communication signal interfaces according to inputted RFsignals in real time.

At least one embodiment of the present invention provides a contactlessintegrated circuit (IC) card. Such an contactless IC can include: ananalog interface block operable to demodulate a received radio frequency(RF) signal into multiple versions thereof according to a firstplurality of communication protocols, respectively; a controlleroperable to select from among a second plurality of communicationprotocols; and a universal asynchronous receiver/transmitter (UART)operable to select one of the demodulated versions of the RF signalaccording to the selected protocol

Additional advantages, objects, and features of the present inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of thepresent invention. The objectives and other advantages of the presentinvention may be realized and attained by the structure particularlypointed out in the written description and claims hereof as well as theappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present invention and are incorporated in andconstitute a part of this application, illustrate embodiment(s) of thepresent invention and together with the description serve to explain theprinciple of the present invention. In the drawings:

FIG. 1 is a schematic block diagram of a contactless IC card, accordingto at least one embodiment of the present invention;

FIG. 2 is a block diagram of an analog interface block of FIG. 1,according to at least one embodiment of the present invention;

FIG. 3 illustrates a signal demodulated by demodulator circuits of FIG.2 in a type-A communication, according to at least one embodiment of thepresent invention;

FIG. 4 illustrates a signal demodulated by demodulator circuits of FIG.2 in a type-B communication, according to at least one embodiment of thepresent invention;

FIG. 5 is a more-detailed block diagram of a universal asynchronousreceiver/transmitter of FIG. 1, according to at least one embodiment ofthe present invention;

FIG. 6 is a schematic block diagram of a contactless IC card, accordingto at least one other embodiment of the present invention; and

FIG. 7 is a more-detailed block diagram of a universal asynchronousreceiver/transmitter of FIG. 6, according to at least one otherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Reference will now be made in detail to the example embodiments of thepresent invention, which are illustrated in the accompanying drawings.However, the present invention is not limited to the example embodimentsillustrated herein after, and the example embodiments herein are ratherintroduced to provide easy and complete understanding of the scope andspirit of the present invention. The terms “communication signalinterface” and “communication protocol” will be used interchangeably.

In developing embodiments of the present invention, the followingproblem with the Background Art was recognized and a path to a solutionidentified. As noted, the Background Art vicinity-type IC cards supporteither the type-A or the type-B interface, but not both, which is aproblem when attempting to use an IC card of one interface type with acard reader of the other type interface. Such a problem can be avoidedby providing an IC card and/or a card reader that is/are compatible withboth type-A and type-B interfaces.

FIG. 1 is a schematic block diagram of a contactless IC card, accordingto at least one embodiment of the present invention. Referring to FIG.1, a contactless IC card 100 includes: a central processing unit 120with an operating system (hereafter, CPU 120); a transmission/reception(TRX) protocol control register 140; a contactless universalasynchronous receiver/transmitter (UART) 160; and an analog interfaceblock 180.

To transmit/receive an RF signal, the type of communication signalinterface is set in the register 140, e.g., initially by an operatingprogram of the contactless IC card 100. Once register 140 is set, theUART 160 and the analog interface block 180 operate accordingly. The TRXprotocol control register 140 controls a protocol transfer rate, anerror verification method, UART start and end transmission/receptionnotification, and the like. The UART 160 codes data (from the CPU 120that are to be transmitted), according to the particular communicationsignal interface that has been set in the register 140 (hereafter, theselected interface type), and outputs the coded data to the analoginterface block 180, e.g., one bit by one bit. The analog interfaceblock 180 modulates the data outputted from the UART 160 according tothe selected interface type and then outputs the modulated data throughan antenna 200. Correspondingly, the analog interface block 180demodulates an RF signal received via the antenna 200 according to theselected interface type, and the UART 160 temporarily stores an outputof the analog interface block 180 according to the selected interfacetype. The stored data are transmitted to the CPU 120.

FIG. 2 is a more-detailed block diagram of the analog interface block180 of FIG. 1, according to at least one embodiment of the presentinvention. Referring to FIG. 2, the analog interface block 180 includes:a coil 401; a variable capacitance 409, a rectifier 402; a DC shuntregulator 403; a type-B demodulator 405; a reset interface 407; a type-Ademodulator 404; a clock extractor 406; and an ISO modulator 408. Therectifier 402 converts an AC signal into a DC voltage and iselectronically connected to a coil 401. Based on the DC voltageoutputted from the rectifier 402, a DC shunt regulator 403 generates apower supply voltage VDD necessary when driving internal circuits of theIC card 100. A type-A (ASK 100% modulation) demodulator 404 demodulatesreception information contained in AC signal received through the coil401, and a type-B (ASK 10% modulation) demodulator 405 demodulatesreception information contained in an output of the rectifier 402.

FIG. 3 illustrates signals demodulated by the demodulators 404 and 405when RF signals are received from a card reader having a type-Ainterface according to at least one embodiment of the present invention.FIG. 4 illustrates signals demodulated by the demodulators 404 and 405when RF signals are received from a card reader having a type-Binterface, according to at least one embodiment of the presentinvention. As can be seen in FIG. 3, when RF signals are received fromthe card reader having the type-A interface, the signals demodulated bythe demodulators 404 and 405 have the same waveforms. As can be seenfrom FIG. 4, when RF signals are received from the card reader havingthe type-B interface, the signal demodulated by the demodulator 404maintains a constant level while the signal demodulated by thedemodulator 405 has a demodulated waveform that is characteristic of thetype-B interface.

Referring again to FIG. 2, the clock extractor 406 is configured toextract a clock signal RF_CLK from the AC signal received through thecoil 401, and the reset interface 407 is configured to generate a resetsignal RST based on the output of the rectifier 402. The ISO modulator408 modulates data TX_A/B outputted from the UART 160 according to theselected interface type.

FIG. 5 is a more-detailed block diagram of the universal asynchronousreceiver/transmitter (again UART) 160 of FIG. 1, according to at leastone embodiment of the present invention. The UART 160 includes: atransmission/reception (again, TRX) control block 161; a shift register162; a code conversion block 163; a timing and control block 164; aparity control block 165; a CRC block 166; and a header detection block167.

Referring to FIG. 5, the CPU 120 transmits control signals relating toprotocol setup and UART driving, transmission/reception mode,transmission/reception rate, error handling method, protocolimplementation option, transmission/reception end control, and the like,to the TRX control block 161. The TRX control block 161 controls a flowof UART operation. Transmission data are shifted out of the shiftregister 162, e.g., out of the LSB position, e.g., one bit by one bit,e.g., periodically, and then transmitted to a transmission codeconversion block 163 a. The transmission code conversion block 163 aconverts the inputted transmission data into code data according to theselected interface type. The code data converted in this manner aremodulated by the analog interface block 180 and the modulated signalsare transmitted to the card reader or the terminal through the antenna200. If the type-A communication signal interface is selected, then thetransmission code conversion block 163 a adds parity information,obtained from the panty control block 165, to the data outputted fromthe shift register 162.

The RF signal received via the antenna 200 is individually demodulatedthrough the demodulators 404 and 405 of the analog interface block 180(resulting in multiple demodulated versions of the RF signal), and thenthe demodulated signals are transmitted to the code conversion block163. Modified mirror code signals demodulated by the demodulator 404 areconverted into NRZ-L codes by a reception code conversion block 163 b. Aselector 163 c selectively outputs an output of the reception codeconversion block 163 b and the signal demodulated by the demodulator405, according to the selected interface. The data outputted from thecode conversion block 163 are inputted to the shift register 162, e.g.,at the LSB position, e.g., one bit by one bit. If the shift registerbecomes filled, e.g., with data representing a one-byte unit, then thedata stored in the shift register 162 is transmitted to the CPU 120. Forexample, if the shift register 162 becomes completely filled, then theTRX control block 161 outputs an interrupt signal to the CPU 120, andthen, the CPU 120 takes the data stored in the shift register 162 inresponse to the interrupt signal.

A control and timing control block 164 receives a clock from the analoginterface block 180 and generates a clock for the UART 160 under thecontrol of the TRX control block 161. If the type-A interface isselected, then the parity control block 165 determines whether or notthere is a parity error in a reception operation, and then, generatesparity information regarding the transmission data during a transmissionoperation. The cyclic redundancy checking (again, CRC) block 166 isconfigured to determine whether or not there is an error within thetransmitted data. The header detection block 167 receives the signalsdemodulated by the analog interface block 180 and detects headerinformation (for example, SOF information in case of the type-Binterface) of a current input signal. The TRX control block 161 controlsthe shift register 162 according to the detected result of the headerdetection block 167.

If the contactless IC card 100 is set to the type-A of the communicationsignal interface, then the contactless IC card 100 can communicate withonly a card reader having the type-A of the communication signalinterface, and vice versa. In other words, despite having the capabilityto work with either interface, the contactless IC card 100 will onlywork with one or the other of the interfaces unless a change is made tothe setting in register 140. Accordingly, an alternative arrangement ofcontactless IC card 100 includes an optional toggle capability to switchthe communication signal interface set in register 140 between type-Aand type-B, e.g., periodically. With such a toggling capability, it ispossible to communicate with a card reader having the type-B interface,as well as a card reader having the type-A interface. Such switchingcapability can be provided using additional, e.g., hardware (forexample, a timer 121 indicated as being optional via the use of dashedlines) or software (for example, running on CPU 120), etc.

FIG. 6 is a schematic block diagram of a contactless IC card accordingto at least one other embodiment of the present invention. Referring toFIG. 6, the contactless IC card 300 includes: a central processing unit320 with an operating system (hereafter, CPU 360); atransmission/reception (again, TRX) protocol control register 340; auniversal asynchronous receiver/transmitter (again, UART) 360; an analoginterface block 380; and a flag register 400.

The contactless IC card 300 performs the following processes beforesetting a communication signal interface. First, the contactless IC cardis set to a reception mode under the control of the CPU 320 in order toreceive RF signals of either type-A and type-B. Then, a basic option ofthe UART 360 is set and the UART 360 is driven. This condition is acommunication ready state between the contactless IC card and a cardreader whose communication signal interface is not known. When a cardreader transmits an RF signal, the received RF signal is demodulatedthrough the analog interface block 380 individually according to boththe type-A and type-B interface (resulting in multiple demodulatedversions of the RF signal), and the first and second demodulated signalsare transmitted to the UART 360.

The UART 360 determines the interface type according to which the RFsignal is compliant based upon at least one of the demodulated signalsand transmits the identified type to the flag register 400. Finally, theCPU 320 sets values in the register 340 according to the value stored inthe flag register 400 corresponding to the identified type.

Thereafter, the contactless IC card 300 communicates with a terminalaccording to the identified interface type. If RF signals of the othercommunication signal interface are received, the UART 360 adaptivelychanges the value stored in the flag register 400 and then the CPU 320adaptively switches the communication signal interface according to thechanged value.

In the contactless IC card 300, the analog interface block 380 of FIG. 6is configured with a structure substantially identical to that of FIG.2. Therefore, its detailed description will be omitted.

FIG. 7 is a more-detailed block diagram of the UART of FIG. 6, accordingto at least one other embodiment of the present invention. The UART 360includes: a transmission/reception (TRX) control block 361; a block 410of shift registers; a block 412 of code converters; a header detector367; a parity control block and a CRC block 420.

Referring to FIG. 7, the transmission data are shifted out of thetransmission shift register 362, e.g., out of the LSB position, e.g.,periodically, e.g., bit-by-bit, under the control of the TRX controlblock 361 and transmitted to a transmission code conversion block 363 inthe block 412. The transmission code conversion block 363 converts thetransmission data into code data according to the selected interfacetype. The converted code data are modulated through an ISO modulator 408of the analog interface block 380 (again, see FIG. 2), and the modulatedsignals are transmitted to the card reader or the terminal through theantenna 200.

The signals received by the contactless IC card 300 via the antenna 200are individually demodulated into codes of type-A and type-B via thedemodulators 404 and 405 of the analog interface block 380 (again, seeFIG. 2). The signals demodulated by the demodulator 404 are convertedinto NRZ-L code data via reception code conversion block 364 of block412 and the converted data are outputted to a type-A interface of block410 shift register 365. The signals demodulated by the demodulator 405are outputted to a type-B interface shift register 366 without any codeconversion. The header detection block 367 detects whether or not SOFinformation is contained in a header portion of the signal demodulatedby the demodulator 404. The TRX control block 361 sets a value of theflag register 400 according to the detected result.

A parity control block 368 determines whether or not there is a parityerror when the contactless IC card is set to the type-A of theinterface, and generates parity information regarding the transmissiondata in a transmission operation. A clock and timing control block 369receives a clock from the analog interface block 380 and generates aclock for the UART 360. A CRC block 420 is configured to check whetheror not there is an error within the transmitted data.

Unlike the contactless IC card 100, the contactless IC card 300 does notcommunicate with the card reader according to a previously selectedinterface stored in the register 340 but communicates with the cardreader after analyzing the RF signals transmitted from the card readerin real time and adaptively setting the interface type in the register340 according to the analyzed result. The selected interface type isswitched in real time to match that of the card reader.

For example, in the type-A communication, the card reader transmits ashort frame signal as a REQA command (26H or 0110010B) to thecontactless IC card 300. Each of the demodulators 404 and 405 of theanalog interface block 380 demodulates the inputted short frame signal.As described above (see FIGS. 3-4), if the RF signals of type-A arereceived, then the signals demodulated individually by the demodulators404 and 405 have the same waveforms. The signals demodulated by thedemodulator 404 are converted from modified mirror codes to NRZ-L codesthrough the code conversion block 364. At the same time, the headerdetection block 367 detects whether or not SOF information is containedin a header portion of the signal demodulated by the demodulator 405. Inthe type-A communication, the TRX control block 361 will recognize thatSOF information is not contained in the header portion of thedemodulated signal and accordingly sets a value in the flag register400, and then transmits an interrupt signal to the CPU 320. The CPU 320correspondingly sets values in the register 340 based upon the contentsof the flag register 400, and then the UART 360 and the analog interfaceblock 380 operate according to the type-A interface. Thereafter, thecontactless IC card 300 communicates with the card reader using thetype-A interface.

On the other hand, in the type-B communication, the card readertransmits a frame signal as a REQB command (050000H) to the contactlessIC card 300. Each of the demodulators 404 and 405 of the analoginterface block 380 demodulates the inputted short frame signal. Asdescribed above (again, see FIGS. 3-4), when the RF signals of type-Bare received, the signal demodulated by the demodulator 404 maintains aconstant level while the signal demodulated by the demodulator 405 has awaveform shown in FIG. 4. Since the signal demodulated by thedemodulator 405 has a NRZ-L code format, the demodulated signal istransmitted to the type-B reception shift register 366 without any codeconversion. At the same time, the header detection block 367 detectswhether or not SOF information is contained in a header portion of thesignal demodulated by the demodulator 405. The TRX control block 361sets a value of the flag register 400 according to the detected resultof the header detection block 367 and transmits an interrupt signal tothe CPU 320.

In the type-B communication, the TRX control block 361 will recognizethat SOF information is contained in the header portion of the signaldemodulated by the demodulator 405, and then the TRX control block 361will set a corresponding value in the flag register 400 and send aninterrupt signal to the CPU 320. The CPU 320 correspondingly sets valuesin the register 340 based upon the contents of the flag register 400,and then the UART 360 and the analog interface block 380 operateaccording to the type-B interface. Thereafter, the contactless IC card300 communicates with the card reader using the type-B interface. Afterthe setting of the communication signal interface, blocks related to anunselected communication signal interface can be set to a suspend modein order to reduce power consumption. For example, this can be achievedby selectively controlling the clocks generated by the clock and timingcontrol block 369. Alternatively, it is possible to reduce powerconsumption by controlling the components of the analog interface block380 (for example, the demodulators) according to the selected interface.

The above description the contactless IC cards 100 and 300 in terms ofthe type-A and type-B interface operation is one example of the how thepresent invention can be embodied. However, by appropriately configuringthe analog interface block 180/380, such a contactless IC card can alsocommunicate in real time with a card reader having a communicationsignal interface other than or in addition to the type-A and type-Binterfaces, and accordingly configuring the UART 160/360, etc. In FIGS.6 and 7, it should be apparent to those skilled in the art that the flagregister 400 alternatively can be contained in the DART 360 or the TRXcontrol block 361.

As described above, the contactless IC card 300 can communicate withcard readers using various communication protocols by analyzing thecommunication protocol being used and adaptively setting the register340 accordingly, all in real time.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A contactless integrated circuit card comprising: an analog interface block operable to demodulate a received radio frequency (RF) signal into multiple versions thereof according to a first plurality of communication protocols, respectively; a controller operable to select a protocol from among a second plurality of communication protocols; and a universal asynchronous receiver/transmitter (UART) operable to select one of the demodulated versions of the RF signal according to the selected protocol. 